Spiral binder



Q l Z 1941. E. N. FARKAS SPIRAL BINDER Filed Feb. 29, 1940 INVENTOR nm'(L ATTORNEY Patented Sept. 23, 1941 '1'- OFFICE srmar. amnan Emil N.Farkas, Chicago, 111., assilnor, by direct and mesne cage, 111., astrustee assignmentl,toEmi1N Paths 0111 Application February 29, 1940,Serial P1023213 This invention relates to new and useful improvements inbinders for, and a method of assembling in book form of marginallyperforated leaves.

More particularly, the present invention is an improvement on thespiraLbinder of plastic and highly resilient material disclosed inPatent No. 2,188,680 to. Frank F. Farkas, and its object is to preformthe binder so that a book bound with it will open with leaves inregistry. This I accoma plish by forming each loop of the binder so thatthe helix will have a compound rather than a simple pitch. The spiral isso resilient that it.

may be. readily threaded through the uniformly and equally spacedmarginal perforations of a stack of leaves without deformation oftearingof the binder or leaves. The curvatures r slopes of the two halves ofeach loop are so altered with respect to one another that when thebook-isopened the two exposed pages engaging opposed points of a loopwill be in registry with one another rather than vertically displaced aswould be the case if the halves of the loops were uniform.

According to the present invention the binder vis formed and set withthe loops having the required contours during its manufacture and beforeit is threaded through the book perforations, thus avoiding thenecessity of special operations on the finished book. The invention willnow be fully explained with reference to the drawing in which i Fig. 1is a plan view of one embodiment of my invention at an intermediatestage of its manufacture;

Fig. 2 is a side elevation of a book bound in accordance with thepresent invention;

Fig. 3 is a side elevation of a spiral binder constructed in accordancewith a second embodiment of the invention;

Fig. 4 is a plan view of a third embodiment at an intermediate stage ofits manufacture; and

Fig. 5 shows holes suitable for easy insertion of a spiral formed of thestrip in Fig. 4.

Referring now to the drawing, I is a thin fiat strip of plastic materialhaving parallel edges and which is so pliable that it can be readilydeformed and yet sumciently resilient to retain its preformed shape whensubjected to normal strains after it is formed into a helical coil.

One edge of strip 1 is mutilated by cutting out unsymmetrical wedges 2at intervals determined by the diameter required-for the loops of thehelix. The cut-out occupies about one-half the length required for eachloop.

The strip is wound on a mandrel of suitable diameter into a helical coiland subjected to heat and pressure to set it. The strip 1 will thus beformed into a cylinder. When the loops of which 5 the cylinder v is madeup 'are pulled out to form' open'coil, each loop. as far as theedges'viewed from the side are concerned, will have-two differentcurvatures: the unmutilated portions,

'i. e;, the left-hand edge'and the right-hand edge for about one-half ofeach loop will form substantially a semicircle, and the mutilatedportionswill have a different contour, they may be horizontal. In otherwords the coil will have a compound instead of a uniform or simplepitch.

Thecoil thus formed is sufficiently resilient to permit its threadinginto the marginal perforations 3 of leaves 4. When a book thus bound isopened theper'forations in the right-hand and left-hand leaves will bein alignment since the upper ends of the perforations in the right-handleaves rest on portions of loops having a curvature different from thoseportions which bear against the perforations of the left-hand leaves; Asindicated in dotted linesin Fig. 2, if the 26 wedges were not cut outof. the ribbon and the.

loops of the helix were of uniform configuration,'then the right-handleaves of the opened 5 substantially on a radius and the other half.

straight or with any other different curvature, as indicated at 5 and 6.When inserted through. the perforations of a book, the left-hand leavesof the opened book will engage portions! and the so right-hand leavesportions 8 of the helix. Since these portions are substantially inalignment, the leaves will be in registry. i

This embodiment is particularlyrecommended for narrow stock, though itis applicable to wide ribbons also.

-In the embodiment shown in Fig.4 a ribbon in of plastic material isformed with parallel but undulating edges; the undulations beingo! twodifferent curvatures H and I2, alternating throughout the length of thestrip.

When this strip 'is wound on a cylindrical .mandrel and then set, thecoil thus formed will have a compound pitch Just as in- Figs. 2 and 3.

The difference is that whereas the helix of Fig. 2

will have a compound pitch along its upper or supporting edge, the helixformed of strip." will have a compound pitch along both edges;

With this type of coil the perforations in the book leaves must be largeenough to permit threading of the finished coil, and may have other thansymmetrical shapes, 1. e., different from the usual rectangular orcircular holes. I'bur such holes are shown in Fig. 5.

What is claimed is;

1. A binder for sheets having marginal periorations, consisting of alength of plastic material preformed into a substantially compound pitchhelical coil which may be screwed into said perforations, the two halvesof each loop forming, at least along one edge of the length of material,a different angle with the longitudinal axis of the coil.

' both of its edges 8. difierent angle with the longitudinal axis of thecoil than in the other half.

EMIL N. FARKAS.

